Volatile and non-volatile memory devices (e.g., RAM, ROM) frequently include column redundancy circuits to repair one or more defective columns within a memory array block. An example of a memory device that supports column redundancy is disclosed in U.S. Patent Publication No. 2002/0001896 to Yoon. In particular, FIG. 2 of Yoon illustrates a memory device having a plurality of blocks of memory cells therein. Each of these blocks of memory cells is illustrated by the reference characters DQ0–DQn. Memory cell block DQ0 includes a plurality of columns of memory cells 22 that may be selectively coupled to a corresponding global input/output line GIO<0> using a corresponding write driving and read sense amplification unit 26. Similarly, memory cell block DQn includes a plurality of columns of memory cells 32 that may be selectively coupled to a corresponding global input/output line GIO<n> using a corresponding write driving and read sense amplification unit 36. FIG. 2 of Yoon also illustrates a fuse box unit 48 that may be configured so that a plurality of columns of repair memory cells 43 may be used to repair one or more columns within a memory cell block (DQ0–DQn) having at least one defective column of memory cells therein. Unfortunately, the memory device of Yoon may provide an inefficient use of the columns of repair memory cells 43 for those cases where the number of columns of repair memory cells 43 connected to a corresponding repair column decoding unit 45 exceeds a number of defective columns of memory cells within a memory cell block (DQ0–DQn) being repaired. For example, if two or more columns of repair memory cells 43 are associated with each repair column decoding unit 45 , then one or more of these columns of repair memory cells 43 may go unused in the event a memory cell block (DQ0–DQn) being repaired contains only one defective column of memory cells therein. Accordingly, the memory device of Yoon may provide a relatively inefficient means for repairing defective columns within a multi-block memory device.